So I've read and understood all the basics of wheel weights and rotational inertia, but I have a question for those who know more than I do on the subject:

www.wheelweights.net lists the 97-99 16" wheels as weighing 19.6 lbs. Pick a light rim like the SSR GT1 (18x8 = 19.0 lbs.) or the OZ Superleggera (18x8 = 17.6 lbs.). Will it have less roatational inertia because it weighs less, or might it have more because the circumference of the rim is where a lot of the weight is concentrated (and the center of mass is therefore farther from the center, which means more rotational inertia)?

I remember hearing that tire weights actually matter a lot more than rim weights because the tires are furthest from the center. That makes sense. So assuming that low-profile tires weigh less than normal, tall tires (because there's less rubber), wouldn't the total weight, and maybe also the rotational inertia/mass, be less? In other words, if a 16" inch rim and a different 18" rim weigh the same, wouldn't it be logical that the rim-tire combo would weigh LESS for the 18" rim? That might counteract any greater roatational mass that the 18" rim might have. Lighter tires are always a plus, of course.

 

I'm actually pretty sure that the lower profile tires weigh as much if not more than the ones on the stock wheels. Either way, its very difficult to get a set of 18" wheels that are going to end up making your car any faster than a set of 16" wheels. But if you're going for larger wheels and want a light weight tire, get the Pirelli p7000's, they are one of the lightest tires out there.

 

Yup. Lower profile tires tend to be high performance V,Z,W rated etc. Because of that, their sidewalls are thicker to make them less likely to heat up at speed compared to high profile tires. Those thicker sidewalls make them the same weight or heavier than their high profile counter parts. You can't win for losing.

It's good to know that the P7000s are light. Now, there are 2 types of P7000s, the P7000 and the P7000SS (SuperSports). Are they both light?? The SS is the cheaper one b/c it's made of a harder rubber that lasts a very long time. The non SS uses stciky rubber for great grip, but they will wear out real quick, too. And the non SS costs more.

DW